HSC Survey Results

Scots Bay Survey # 3 Results from 02/06/2024

Survey Details

6 commercial purse seiners conducted this fishing survey on 02/06/2024 starting at 20:00:00, which was 0.98 hours before hide tide.

All vessels ran two transects each in the Main Survey Box, the Bruswick Provider ran four lines in the Eastern Survey Box, and the Lady Janice ran four lines in the Northern Survey Box.

There was a plankton tow and replicate conducted and CTD cast by Lady Melissa.

No tags were applied during this survey.

Samples were obtained for target strength estimation.

Tides Tables

Tide Schedule for Margaretsville NS, Station #315m Source: www.waterlevels.gc.ca

Acoustic Equipment

Each vessel was equipped with a Simrad ES38-18/200-18C combi (2-in-1) transducer prior to the survey that contains a 38kHz split beam and 200 kHz single beam transducer. Data was logged to the computer hard-drive for post-processing. All participating boats were calibrated on 38kHz before the survey.

Survey Results

Main Results

The results are subject to change as DFO will re-evaluate data editing, area estimation and apply a target strength.

Preliminary biomass prediction for Scots Bay using standardized parallel transects is 93,805mt, and with turnover applied 89,523mt.

Transect Details

Table 1: Transect Details
Vessel Transect # Date/Time Start Date/Time End Start Lon Start Lat End Lon End Lat Location Distance (km) Speed
BP T01 2024-06-02 03:00:00 2024-06-02 03:00:00 -64.687 45.226 -64.551 45.264 SB 11.47 Inf
BP T04 2024-06-02 03:00:00 2024-06-02 03:00:00 -64.553 45.328 -64.758 45.268 SB 17.47 Inf
BP T02 2024-06-02 03:00:00 2024-06-02 03:00:00 -64.558 45.283 -64.715 45.239 SB 13.27 Inf
BP T03 2024-06-02 03:00:00 2024-06-02 03:00:00 -64.735 45.254 -64.549 45.308 SB 15.79 Inf
C1 T01 2024-06-02 03:00:00 2024-06-02 03:00:00 -64.838 45.307 -65.231 45.167 SB 36.48 Inf
C1 T02 2024-06-02 03:00:00 2024-06-03 03:00:00 -65.222 45.098 -64.751 45.254 SB 42.46 0
LM T01 2024-06-02 03:00:00 2024-06-02 03:00:00 -65.229 45.056 -64.702 45.230 SB 46.01 Inf
LM T02 2024-06-02 03:00:00 2024-06-03 03:00:00 -64.788 45.283 -65.234 45.129 SB 39.28 0
MS T01 2024-06-02 03:00:00 2024-06-02 03:00:00 -64.729 45.241 -65.232 45.074 SB 45.09 Inf
MS T02 2024-06-02 03:00:00 2024-06-03 03:00:00 -65.232 45.149 -64.817 45.294 SB 39.04 0

Survey Summary

Table 2: Acoustic Survey Results
Vessel Transect No.  Target Strength (db/kg) Mean Sa (/m2) Biomass Density (kg/m2)
C1 T01 -35.5 -36.202 0.851
LJ T04 -35.5 -39.558 0.393
LJ T03 -35.5 -39.759 0.375
LJ T02 -35.5 -39.843 0.368
BP T01 -35.5 -44.328 0.131
LJ T01 -35.5 -52.643 0.019
LM T02 -35.5 -53.396 0.016
FM T02 -35.5 -54.165 0.014
FM T01 -35.5 -54.381 0.013
BP T04 -35.5 -56.053 0.009
LM T01 -35.5 -56.221 0.008
C1 T02 -35.5 -56.295 0.008
MS T01 -35.5 -57.877 0.006
BP T03 -35.5 -65.546 0.001
BP T02 -35.5 -71.586 0.000
MS T02 -35.5 -80.767 0.000
Note:
Transects are listed from greatest to least backscatter.
Table 3: Survey Summary Table
Layer Target Strength Area (km2) Mean Sa Density (kg/m2) Biomass (tons) Percent Area Percent Biomass Standard Error (tons) Standard Error (%)
Main Box -35.5 631.58 -45.4593 0.1145 63,752.188 75.1 68.0 66,442.14 104.22
Northern Box -35.5 88.27 -40.7147 0.2888 26,566.843 10.5 28.3 7,941.38 29.89
Eastern Box -35.5 120.71 -50.8946 0.0353 3,485.621 14.4 3.7 3,858.29 110.69

Greatest Biomass Densities

A snip from the transect with the greatest biomass density (kg/m2)

A snip from the transect with the greatest biomass density (kg/m2)

The single point with the largest biomass density (kg/m2) was recorded by C1, at the following location:

The transect with the greatest average biomass density (kg/m2) was recorded by C1, at the following location:

Annual Summaries

Table 4: Annual Comparison Table
Current Year
Previous Year
Ground Survey Number Survey Date HSC Estimate HSC Turnover Adjusted Survey Date HSC Estimate HSC Turnover Adjusted DFO Estimate DFO Turnover Adjusted
Scots Bay 1 2024-05-05 78,662 NA 2023-05-22 40,856.000 40,856 0 0
Scots Bay 2 2024-05-20 29,842 17,255 2023-06-06 113,767.329 108,783 NA NA
Scots Bay 3 2024-06-02 93,804 89,523 2023-06-18 34,279.387 15,158 NA NA
Scots Bay 4 NA NA NA 2023-07-02 11,744.776 5,113 NA NA
Scots Bay 5 NA NA NA 2023-07-16 19,282.634 17,575 NA NA
Scots Bay 6 NA NA NA 2023-07-30 4,549.933 1,904 NA NA
Scots Bay 7 NA NA NA 2023-08-13 4,298.806 3,616 NA NA
Scots Bay 9 NA NA NA 2023-09-10 3,053.669 2,916 NA NA
Scots Bay 10 NA NA NA 2023-09-24 3,419.932 2,997 NA NA
Scots Bay 8 NA NA NA 2023-08-27 2,896.659 2,300 NA NA
Scots Bay 11 NA NA NA 2023-10-09 3,387.515 2,971 NA NA
Table 5: Annual Summary Table
Year Ground HSC Estimate HSC Turnover Adjusted DFO Estimate DFO Turnover Adjusted
2023 Scots Bay 241,536.6 204,189 NA NA
2024 Scots Bay 202,308.0 106,778 NA NA

Tagging, Plankton, and CTD Data

Tag Data

Vessel Tags

Plankton Data

Tow Summary Table

Tow 1
Tow 2
Base Details
Vessel Lady Melissa Lady Melissa
Set Number SB2024-05 SB2024-06
Ground SB SB
Date 02/06/2024 02/06/2024
Wind Direction (km/h) NW NW
Swell (m) 0.5 0.5
Air Temp (c) 16 16
Tow Details
Tow Start 18:47:00 19:05:00
Tow End 18:57:00 19:15:00
Start Lat 45.053 45.065
End Lat 45.07017 45.05617
Start Lon -65.24650 -65.21133
End Lon -65.22883 -65.20517
Avg Tow Depth (m) 9.939442 16.736816
Speed NA NA
Heading NA NA
Tide Direction with against
Other Data Collection
Flow Start 863527 926786
Flow End 926786 982864
No. Revolutions 63259 56078
Distance (m) 1699.959 1506.984
Volume 5340.422 4734.191
Secchi Disappear (m) 8.5 8.5
Secchi Reappear (m) 7 7

Tow Depth Profiles

Plankton tow depth profile #1

Plankton tow depth profile #1

Plankton tow depth profile #2

Plankton tow depth profile #2

The first tow is SB2024-05, which was with the tide and had an average depth of 9.9394418m. The second tow is SB2024-06, which was against the tide and had an average depth of 16.7368157m.

Captured plankton

Captured plankton from the surface tows

Captured plankton from the surface tows

CTD Data

CTD depth profiles for all 2024 Scots Bay surveys so far.

Sea surface temperatures

Annual average sea surface temperatures (SST) for Scots Bay.

Vessel Performance

Speed

Average vessel speed was Inf. This is above the 8 knot requirement; vessels are urged to slow down to prevent backscatter noise from interfering with the acoustic data.

Distance

No significant distance was cut from the planned lines; vessels covered the planned area well.